Direct-injection and PDK for Carrera 4

Only Porsche 911 pedants will spot the upgraded 997-type Carrera 4 range for the 2009 model year. There's a suspicion that even Porsche staff will be struggling to identify the old from the new.

When the press release for the car glosses over the visual changes with an anodyne phrase such as "the discreet but striking modification of the front end" and goes on to mention the latest bi-xenon headlight technology, LED running lights and revised tail lights, that suspicion is confirmed.

The new Carrera 4 is 44mm wider at the rear than the Carrera 2 models recently announced (more here) and a further clue comes from the new reflective panel between the tail lights.

As is the way with Porsche, there's more going on under the skin. The all-wheel drive Carrera 4 and higher-performance Carrera 4S variants will go on sale from October 25, just over a month after the rear-wheel drive Carrera 2 models. Porsche is yet to announce Australian market pricing, but that information will be released in the next few weeks.

Both the Carrera 4 and 4S models will be available in Coupe and Cabriolet guise. As for the Carrera 2 variants, the all-wheel drive 911 will offer Porsche's new PDK ('Porsche Doppelkupplung') transmission as an option. This transmission is ultimately more efficient than both the epicyclic 'Tiptronic S' automatic transmission it replaces and the continuing manual transmission fitted as standard to the 911 models. Porsche owes a debt to Volkswagen's DSG transmission for the PDK.

In common with the VW type, the PDK features a twin-clutch system that allows pre-selection of gears in a manual-type transmission that works in automatic ('Drive') mode by default. Where the standard manual transmission provides six forward speeds, the PDK goes one better with seven. Gear changes are effected smoothly through a computer-controlled electro-hydraulic system.

Arguably more important than the new transmission is the 911's direct-injection petrol engine. Still a flat six, the new engine is available in 3.6-litre and 3.8-litre displacements.

The smaller engine powers the Carrera 4 and improves on the previous port-injected 3.6-litre engine with 8.5 per cent more power and a 12.9 per cent reduction in fuel use. Peak power is 254kW -- a 15kW gain -- and the engine coupled to the PDK transmission uses just 10.1L/100km.

For the larger engine, peak power has increased by 22kW to 283kW and fuel consumption is 10.7L/100km with the PDK box.

For the new Carrera 4 models, Porsche has adapted and modified the electronically controlled 'Porsche Traction Management' system (PTM) from the 911 Turbo to replace the viscous multi-plate clutch all-wheel drive system fitted to the superseded Carrera 4 models. The company claims improved stability, traction and handling from the new drive system, which complements the rear limited-slip differential.

Adaptive cornering lights, which Porsche calls 'Dynamic Bending Lights' are a new option and other changes include a touch-screen to interface with navigation, information and audio systems in the new Porsche Communication Management facility. PCM now provides Bluetooth connectivity, USB audio and iPod compatibility.

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